Date: Mon, 26 Oct 2015 15:21:23 -0500
From: Austin English <austinenglish@...il.com>
To: cve-assign@...re.org, Austin English <austinenglish@...il.com>,
oss-security@...ts.openwall.com
Subject: Re: Re: CVE request for wget
On Thu, Oct 1, 2015 at 6:10 PM, Seth Arnold <seth.arnold@...onical.com> wrote:
> On Thu, Oct 01, 2015 at 06:57:26PM -0400, cve-assign@...re.org wrote:
>> If there is any additional Tails vulnerability related to this,
>> another CVE ID may be needed. For example,
>>
>> https://lists.gnu.org/archive/html/bug-wget/2015-08/msg00050.html
>>
>> says
>>
>> to be 100% sure, you should add --passive-ftp to your command line.
>> If you don't do that, your /etc/wgetrc or ~/.wgetrc could include
>> --no-passive-ftp (or passiveftp = off).
>>
>> If Tails is supposed to try to ensure that, perhaps there's a
>> requirement to have something like:
>>
>> alias wget="wget --passive-ftp"
>>
>> in a system-wide location (possibly /etc/bash.bashrc). The concept of
>> CVE IDs for "failure of a torify step" issues is new, and we aren't
>> sure of the best approach.
>
> I suspect using a bash alias in a site-wide config might then qualify for
> another CVE in the future, along the lines of "programs that spawn wget
> via system(3), popen(3), or exec family of functions can use unsafe active
> mode by accident". If Tails is in the business of fixing these things
> for safety, removing active ftp support from tools seems like better fix.
>
> Thanks
A fix has been applied to Tails git:
https://labs.riseup.net/code/projects/tails/repository/revisions/b9fd6312435d55dd0bc0b6abdb7994da4d66e2b2
In short, the wget binary is moved to /usr/lib/wget/wget, and a
wrapper script is put in place in /usr/bin/wget. The wrapper ensures
that wget is called via torsocks, and additionally, also forces
--passive-ftp.
Moving wget to /usr/lib/wget/wget gets the potentially dangerous wget
binary out of $PATH. A dedicated attacker could check if /usr/bin/wget
is a script and then parse it to find the actual binary, but that
would need to be a very dedicated attacker and at that point, there
are more feasible attacks available.
--
-Austin